1. Field of the Invention
The present invention relates to a magnetic signal recording and reproducing apparatus and a magnetic signal recording and reproducing method for recording and reproducing an information signal on and from a magnetic tape.
2. Description of the Related Art
In magnetic signal recording and reproducing apparatuses using a magnetic tape as a recording medium such as video tape recorders, audio tape recorders, and data storage systems for computers, the helical scan scheme is employed to increase the recording density and hence the recording capacity.
A magnetic tape for the helical scan scheme is formed with recording tracks on which an information signal is recorded in a direction that forms a prescribed angle (azimuth angle) with the longitudinal direction of the tape.
A reproduction magnetic head reproduces an information signal from the magnetic tape by tracing recording tracks. At this time, to allow the magnetic head to reproduce an information signal correctly from the magnetic tape, a tracking control needs to be performed so that the magnetic head traces recording tracks correctly.
To perform tracking correctly, it is necessary to precisely control a magnetic tape feeding system, the rotation phase of a rotary drum, etc. and hence the apparatus configuration becomes complex. As for the magnetic tape, to allow a magnetic head to trace recording tracks correctly, it is necessary that the recording track width be larger than a certain value, which prevents the recording density from being increased.
In contrast, what is called a non-tracking magnetic signal recording and reproducing apparatus has been proposed which can reproduce an information signal from a magnetic tape without the need for performing a tracking control.
In the non-tracking magnetic signal recording and reproducing apparatus, an information signal on recording tracks is detected by tracing the recording tracks at a double density by using a plurality of (e.g., two) reproduction magnetic heads for one recording magnetic head. The information signal is reproduced by recombining resulting signals on a memory.
However, in the above-described non-tracking recording and reproduction, recombining reproduction data on the memory requires that the magnetic heads perform tracing plural times. Therefore, it is necessary to use a large-capacity memory as the memory for recombining of reproduction data. Further, since no tracking control is performed, the number of times of tracing to be performed by the magnetic heads to recombine reproduction data on the memory is indefinite. Therefore, if the memory capacity for recombining of reproduction data is insufficient, overflow may occur in the memory.
In view of the above, the present inventors have proposed, in Japanese Unexamined Patent Publication No. Hei. 9-171605, a scheme in which a signal for tracking is provided in a portion of each recording track of a magnetic tape and tracking is performed only on those locations.
However, the conventional recording and reproducing scheme has a problem that it is difficult to insert-rewrite only information to a portion of a recording track because it is unknown at which position on the recording track a magnetic head is made on-track or off-track.
The present invention has been made in view of the above circumstances in the art, and an object of the invention is therefore to provide a magnetic signal recording and reproducing apparatus and a magnetic signal recording and reproducing method that can decrease the track width and increase the recording density as well as can insert-rewrite information to a portion of each recording track.
The invention provides a helical scan type magnetic signal recording and reproducing apparatus which records and reproduces an information signal on and from a magnetic tape on which tracking signals for tracking control are recorded on portions of respective recording tracks, comprising a rotary drum that is approximately cylindrical; magnetic field applying means mounted on the rotary drum, for magnetically recording an information signal on the magnetic tape; magnetic field detecting means mounted on the rotary drum, for magnetically detecting signals from the magnetic tape; signal processing means for reproducing an information signal by performing prescribed signal processing on the signals detected by the magnetic field detecting means; and tracking control means for performing a tracking control on the magnetic field applying means or the magnetic field detecting means based on the tracking signals during recording of the information signal or reproduction on or from the magnetic tape, wherein the magnetic field applying means records the information signal on a portion of a recording track in a state that the tracking control is performed by the tracking control means; the magnetic field detecting means detects the signals from a recording track by tracing the recording track plural times in a state that the tracking control is performed by the tracking control means; and the signal processing means reproduces an information signal by performing prescribed signal processing on signals detected by the magnetic field detecting means.
In the above magnetic signal recording and reproducing apparatus according to the invention, since the tracking control means for performing a tracking control on the magnetic field applying means or the magnetic field detecting means based on the tracking signals is provided, the positioning of a magnetic tape is clarified during recording or reproduction. In this magnetic signal recording and reproducing apparatus, when the magnetic field applying means records an information signal on a portion of a recording track, the magnetic field applying means is made on-track at a prescribed position of the recording track almost without fail.
Further, in the above magnetic signal recording and reproducing apparatus, since the signal processing means for reproducing an information signal by performing prescribed signal processing on signals detected by the magnetic field detecting means is provided, an information signal is reproduced from a magnetic tape even if an off-track state occurs during reproduction.
The invention also provides a magnetic signal recording and reproducing method for recording and reproducing, according to a helical scan scheme, an information signal on and from a magnetic tape on which tracking signals for tracking control are recorded in portions of respective recording tracks, comprising the steps of causing magnetic field applying means to record an information signal on portions of respective recording tracks of the magnetic tape while performing a tracking control based on the tracking signals; and causing magnetic field detecting means to detect signals from recording tracks of the magnetic tape by tracing the recording tracks plural times while performing a tracking control based on the tracking signals, and reproducing an information signal by performing prescribed signal processing on the detected signals.
In the above magnetic signal recording and reproducing method according to the invention, since a tracking control is performed based on the tracking signals, the positioning of a magnetic tape is clarified during recording or reproduction. In this magnetic signal recording and reproducing method, when the magnetic field applying means records an information signal on a portion of a recording track, the magnetic field applying means is made on-track at a prescribed position of the recording track almost without fail.
Further, in the above magnetic signal recording and reproducing method, since prescribed signal processing is performed on signals detected by the magnetic field detecting means, an information signal is reproduced from a magnetic tape even if an off-track state occurs during reproduction.